Carole, theres two things you need to get urgently! One is a firewall. This stops people from accessing your computer. Plus a pop-up stopper. This stops those annoying pop-up adds that slow your connection. Also it's wise to get an "ad-aware" program. this will kill all those trojans hidden and those adds that send your info out.
I reccomend zone alarm for a fire wall, the basic package is a free download. Pop-Up blocker is another program you can download free, (i think it's still free). Plus google search "ad-Aware", this will find you the program to get rid of adds etc. It should also be free.

If you are getting a lot of pop-ups, chances are that your computer is infected allready, so might be best not to delay.