Changing git branches is simple. For example, if you were on the streaming_support branch, and want to change to master, simple do:
git checkout master
If you have changed any files that are tracked by git, git will complain and show what those files are. Commit and push those files, then try checking out master again.
Once you are on the master branch, and want to merge the streaming_support branch into the master branch, do:
git merge streaming_support
In the best case, there are no conflicts and all files are merged automatically. Commit, push, then you are done. If it has been a while since the second branch was created, or since the last merge, then most likely there will be conflicts. Git will show which files have conflicts. You need to go into those files and merge them manually (search for <<<< in the file). After merging, commit and push.