A merge conflict means that you have made some change to files on your local repository, resulting in differences between them and those on the remote repository. Git prevents you from merging with the above error so that you do not lose any of your work. If you don't care about what you've changed, there should be a force merge option (likewise, a force push option to get around the first error). Please note, however, that this would mean losing versions of your files, in effect defeating the whole purpose of git. Ideally, you should resolve your merge conflicts before continuing - this may be easier to do directly from the command line from within your git repo. There's a lot of info on the web about this kind of stuff:
How to resolve merge conflicts in Git?