Well done! Now you have studied all the letters. Let's now recap:
The soft sign ь it makes the letter before it soft. You pronounce the sign like the letter y in yet.
The hard sign ъ makes the letter before it hard. You pronounce the sign as a pause in the word.
To consolidate all of our knowledge, let's write a full sentence in Russian. It will be: Ja uzhje znaju russkije bukvy.