how to use only some letters
I cant understand what i need to do.

I want hashcat to only use some letters that i specify. 
like qwertyasdfgzxcvb123456789 and only does for a password of lengt 6-10 . 
how should i set the commands ?
Unfortunately, I can't do more than link you to the wiki page that explains it very well (what I mean is, I can't read or understand it for you, just spend some minutes and you will get it! you can even use hashcat's --stdout parameter if you want to play around).

hint: --custom-charset2 qwertyasdfgzxcvb123456789 --increment --increment-min 6 --increment-max 10 ?2?2?2?2?2?2?2?2?2?2
Thank you philsmd , i have read that page before but didnt understand, your example was good for me to get it.
Thank you again.