New and lost with modifying custom Themes

Hi,
I am thinking of moving my blogger blog 9custom domain) to wordpress and have started a test blog .(

I already Bought a schemermag template (Schemermag/blogger works well on my blogger) .

I Installed that, but have error messsage in featured content on homepage .

Also, How can I change the widgets ? The Logo, the WordPress banner etc.
I cannot find any tutorials on that .
I tried to drag widgets over in the dashboard to the sidebars ,

But the preinstalled ones(video,flickr etc.)
keep showing on the homepage .Even though they are not on my dashboard and I can’t even deactivate the ones I don’t want .

I am pretty frustrated ,
Sorry, I am just used to Blogger,simply pick text or html widget etc. ,enter code and it works.

Do I have to go into the html and change the template everywhere to make widgtes work in wordpress ? None of my plug ins,that I installed are showing .

Sorry, I just don’t know where to start .
None of the themes come with info,how and where to make these changes .

If someonme would be so kind to give me a quick hint where to start ,
I don’t want to give up on WordPress yet .

Thanks ,

version:Version 2.9.2