My computer user name shows as "hec" . . how i can change it ?

yes you must put your own name then it shows your.

Type users in the search/run box.

You'll have to create the new account, give it full admin rights then delete the other accounts.
If I remember rightly you can't delete the guest account, but you can disable it.

i already have an account with my name and admin rights from :
Control Panel\User Accounts and Family Safety\User Accounts
but it still shows as "hec"
also when i open C:\Users i find 4 : guest, hec, public, updatusUser
and the "hec" acound folder i is with a lock . . a little golden lock around the folder

Under Computer Management you should be able to delete the local users.
Delete the profiles (I think its on the Users menu/dialogue) as well.
As log as you logged in as an administrator you should still be able to access and delete folders with a lock on them.
If I remember correctly you just get a little prompt box.

i have opened "computer management" and i deleted the user updates account which not necessarily . . now i have 3 accounts "hec , guest , administrator"
now the hec acount has all my files and the administrator shows as "public" in c/users . . folder
so what am asking is how i can move all the files in the computer account hec to account administrator so i can delete the hec account . .
and i already named my computer "Hameem" and when i try to change the account name to "Hameem" it says it can't be the same same as the computer name ;(
thanks . .

so the only way is reinstall your OS.

What ?  

yes, reinstall your windows there is no way to repair it.