You should have a nocking point set on the bow already? If you do just tie the loop there, even with a string square you will still make minor adjustments anyway.
I think yours is twin cam bow but if its a single a square will be no real help anyway.
There are heaps of vids on setting up your bow on youtube and some are very good make sure you check them out.
You can also make a sling and a stabiliser very easily also.