SVN install/use

Hay ya

I have been off garrys mod for almost a year now and i want to go back into it all, i have only just started using the basic gmod svn updater, but there seems to be more to it? i need someone to tell me step by step as it all seems to be indirect in other forms and wiki’s

any help i will be greatfull for! really struggling and i don’t want to do what i used to do! also the addons this has given me are currupted or i have mis done them, all the stools have lua errors! = console spam!

Help please! very much appresat!

thank you