This is not really the software you want for something like that. You
need something a little more powerful like Photoshop Elements.
I would suggest that you consider downloading the trial version and then
putting in the same question in the tricks area of the Photoshop
Elements area. There are a lot of really capable people there... and
like you, we are all end-users.
This software is more of a think to keep track of your pictures and has
very limited editing capability.
As suggested by Jim you can try downloading the trial version of Photoshop Ellments. In which you will have to launch the Editor where you'll get a tool called the clone stamp tool through which you can easily get rid of small blemishes in any photograph.