"All good things come in threes." :) The basic idea is that you have the "actual" sentence, the basic one that serves as the frame, and also a phrase that contains "zu". This "zu" phrase is a unit and does not like to mingle with the "frame sentence". Like a pearl in an oyster. A "zu" phrase is called an "Infintivgruppe" ("infinitive group") in German. The "zu" phrase is formed as Lee stated. In the easiest case, you have just "zu" + infinitive. "zu gehen", "zu sprechen". With seperable verbs, it goes in the middle: aufstehen -> aufzustehen. And if you want to add an adverb or object, those come in front: "to walk slowly" -> "langsam zu gehen". This order and structure is not affected by the higher level sentence / main sentence, and for almost every case, no elements of the higher level sentence can slip in. But the "zu" phrase takes a grammatical function in the higher level sentence. First of all without an infinitive group: "Lesen ist mein liebstes Hobby." If I replace the subject, "Lesen", it looks like this: "Bücher zu lesen ist mein liebstes Hobby." "Reading books is my favourite hobby." Infintive groups appear in many different situations. Let's return to the "probieren, etwas zu tun" issue. "Ich versuche etwas." "Ich versuche, den Kuchen (mit Sahne) zu verzieren." "I try to ornament the cake (with cream)." This one has even two objects. Those have no relation to the "versuchen"! "Versuchen" only has a relation to the infintive group as a whole. "Ich versuche X." Now with past tense, since you asked for it. "Ich habe etwas versucht." This is the normal order for a main clause. It's correct to say, "Ich habe den Baum zu fällen versucht". But this structure may seem complicated, because while you read/hear the infinitive group, you need to guess that later a "versuchen" will come. So we ususally push the inner part to the end of the sentence. (But it has to be moved completely and unchanged.) "Ich habe versucht, den Baum zu fällen."

Don't think "I have sentences with 3 verbs". Think about the construction, which verb patterns are used, and the equivalent patterns in German. In your example, the construction "to try to do s.th" uses an infinitive together with "to". The German equivalent is "versuchen etwas zu tun". These infinitive constructions ("erweiterte Infinitive") follow different rules than sentences with several verbs without "zu". General rules: - In a main clause, the conjugated verb is in second position. - In a subclause, the conjugated verb is in last position - Infinitives (without "zu") and participles stack at the end in reverse order. Examples: Der Junge hat [2] dem Mädchen ein Buch gegeben [L]. Der Junge kann [2] dem Mädchen ein Buch geben [L]. Der Junge kann [2] dem Mädchen ein Buch gegeben [L-1] haben [L]. Ich weiss, dass der Junge dem Mädchen ein Buch geben [L-1] kann [L]. Ich weiss, dass der Junge dem Mädchen ein Buch gegeben [L-1] hat [L]. Ich weiss, dass der Junge dem Mädchen ein Buch gegeben [L-2] haben [L-1] kann [L]. (More examples: https://www.reddit.com/r/German/wiki/grammar#wiki_sentence_structure) For "erweiterte Infinitive", you can use the same rule for short infinitive clauses, or you can put the infinitive clause after the sentence for longer clauses: Ich versuche [den Baum zu fällen]. Ich habe [den Baum zu fällen] versucht. Ich habe versucht [den Baum zu fällen]. Pay attention to translations when the English pattern doesn't match the German pattern: I want to go to the cinema today. ["to want to do s.th."] I will heute ins Kino gehen. ["etwas tun wollen", no "zu"].

In English you said "cut," but in the case of a tree, you would say "cut down," meaning that the entire tree will be felled (made to fall). Unless you actually mean cut in the sense that only a small piece the of bark will be cut on the tree. In any case, let's use the verb "to cut down" instead. In German, to cut down would be "abholzen." It's a separable verb so you will have to separate "ab" and "holzen" when you conjugate it. In English, you would say "I have tried to cut down the tree." German grammar functions similarly in that the "to cut down the tree" part of the sentence has to be formed in German using "zu." The "zu" part will be placed before most verbs, but in the case of a separable verb, the "zu" gets placed in between the separable prefix and the verb and thus you will get "abzuholzen." Now the German sentence order will look like this: "I have tried the tree to cut down." This isn't natural English, but this demonstrates how it will look with German sentence order. So the result becomes the following sentence: "Ich habe probiert den Baum abzuholzen." I hope this helps in your understanding. Clauses using "zu" are very handy for expressing a broad range of ideas. Keep in mind that the first part of the sentence sets the mood or scenario of the sentence and the second part shows the primary action taking place. If you have more questions, please let me know.