Make an account here >>>
https://sa-mp.im/register
Verify the account (email)
Then I recommend you to download the IMRP client, It's easier for you. Download it here >>>
https://sa-mp.im/server/download
or you can use samp.exe, You have to use the character name you registered at sa-mp.im to log in. Use the underscore ''_'' aswell.