UBB.threads PHP Forum Software Community Forums UBB.threads 7 Version 7 Support Urgent please, is this bad???

My mysql is 900mb and I have used just over half of it.
If I do a backup would it be stored on that server or
in my host web.com's website server?

How do I use the command line to do this?

I know i need to create a backup but also delete some of the content in the database.