Here is a little help about the Tenses
First you have to learn that Tagalog verbs have 3-4 major groups[ for the actor focus verbs] [ -um-, mag-, and m verbs..i think i forgot the other one] ...if you know these already you already know that if a verb belongs to a group it will not be found in the other group.
example the word EAT= KAIN belongs to -um- verbs it means it has its own way how to form the tenses . The other verbs goes the same.
Basic sentence pattern [ I recommend Victoria P. Carlo's book]
verb + actor + [ ng] object + sa [places,dates].
Kumain ako ng ice cream./ I ate an ice cream.
Kumain si Claire ng donut sa Dunkin Donut. / Claire ate donut in Dunkin Donut.
Basically,- um- verbs are the easiest.
we have infinitive form [ we can use this to instruct someone to do the action]
infinitive form in -um- verbs is when you add - um- to the verb
[ the same spelling in past tense but differs in meaning in usage]
Kumain ka ng kanin. / You eat rice. [ i am instructing someone]
Kumain kayo ng gulay. All of you , eat vegetable. [ I am instructing a group to eat by using " kayo"]
past tense of -um- verb
Add -um- before the verb that starts with a vowel.
inom= drink, uminom= drank
Add um in between the first and second letter of the verb. if a verb starts with a consonant:
takbo= run , tumakbo= ran
For future tense
For verbs starting with vowels double the vowel
inom= drink, iinom= will drink
For verbs starting with consonants, double the first syllable:
takbo= run, will run =tatakbo
For present tense
get the root verb: Takbo= run, then double the first syllable TA, it will become tatakbo then insert - um- in between the first and second syllable.
the result is
tUMatakbo
For verbs starting with vowels: IINOM for example. we doubled the vowel of the verb [ from the word inom], then add -um - before the first letter . it will be UMiinom
and yes Object focus verbs exist. another group need to be learned with different rules