I Downloaded a fake Flashplayer and Optimizer pro, HELP!

Hello,
I hope one of you could help me!

I clicked on a link to download a Flashplayer without checking if the source was trustworthy (stupid, I know) :sad:
It downloaded the program which looks different from the normal Adobe Flashplayer and somehow it also downloaded a program called Optimizer pro which keeps popping up.
Now when I open the internet browser it comes up with advertising, it didn't use to.

What can I do? Can someone please guide me in this mess..

THANKS!