Привет, Erick! :) Your question is very interesting!... Although, you made a small mistake in the question - it should be: "Когда пишутся 'ь' и 'ъ'?" . :) So, answering. A. The letter "ъ" is written after the ONLY letters "е", "ё", "ю" and "я", in case of... 1) ... the combination of a prefix (which ends in a consonant) and a root. For example - подъезд ("под" is a prefix, "езд" is a root). 2) ... the compound words consisting of numerals. For example: трёхъязычный ("трёх" means "three", "язычный" means "lingual"). 3) ... foreign prefixes in the word. For example: инъекция, субъект, объект etc. Oooooghhffffff... we have finished with "ъ", so let's go to "ь"! The soft sign - "ь" - is written for ADDING SOFTNESS to the previous consonant and SEPARATING sounds. B. 1) The letter "ь" is written in the word to separate consonants and such the following vowels, as "и", "е", "ё", "ю", "я". For example: карьер ("КАР" and "ЕР"), семья ("СЕМ" and "Я"), ночью ("НОЧЬ" and "Ю"). 2) Also, "ь" is written to add some softness to the consonant (that's why they call this sign a soft one!) - any consonant, besides "ч" and "щ". For example: просьба, нянька, меньше. 3) "Ь" is written in the Plural forms of the Instrumental case. For example: детьми and людьми. 4) ...in the compound words formed from the numerals "пять", "шесть", "семь" etc. For example: пятьдесят, шестьдесят, семьдесят etc. 5) ...in the indefinite forms of a verb. For example: делать, писать, читать etc. 6) ...in the end of such the particles, as "вишь", "бишь", "лишь"... 7) ...in the ending of verbs - the second person, Singular, Future and Present Tense. For example: делаешь, пишешь, читаешь. 8) ...in the ending of verbs of the Imperative mood. For example: ешь, спрячь, мажь. 9) ...in the ending of Feminine nouns of the Nominative or Accusative case. For example: рожь, мышь, ночь. Okay, that's all. I hope that will help you a lot (I was trying to do my best). :)

In addition to the perfect answer above: As for "ы", it's the letter that "и" changes into. (see A. item 1) For example: разыграть (formed from the prefix "раз" and the verb "играть"), отыскать (prefix "от" + verb "искать"), предыдущий (prefix "пред" + adj. "идущий").

правильно пишется, когда "ы" и "ъ" знак используются и как выражаются в письме

ы читается, а ъ в основном идет для разделения приставки от корня , когда корень чаще начинается с глассной (например, объяснить)

чувак, это же обычные буквы, я думаю учить правила тут неуместно...