a little help needed please

[crause]

I am switching over to Gimp from another edit program and could use a little help. I take photographs of rescue dogs to post onto adoption websites, mostly for Labs4rescue. The main thing I do is to remove the leashes from the photo and do a little cropping. I can't figure out how to do that on this program. I can not access the user manual it says that something crashed and to restart my computer. That didn't help. In the previous program I used, I would put the cursor on an area that I wanted to copy and then use the brush to cover over the leash. This worked great. Can anyone teach me how to do this on Gimp?
I thank you and all of the dogs looking for forever homes thank you.