The friendship between Antonio and Bassanio is an important theme in The Merchant of Venice by William Shakespeare. To start on this project, you should break it into several small steps.
My first suggestion would be downloading a free copy of the text of The Merchant of Venice from a site such as the MIT Complete Works of William Shakespeare or Project Gutenberg. This will enable you to do searches of the play for the words "friend" and "friendship", so you can do a complete analysis of how friendship is discussed in the play. You will also be able to search for all of the lines spoken by or about these two characters. If you have difficulty in understanding specific phrases or references, consult the eNotes etext of the play, which includes annotations.
Next, you should look at the role of the friendship in the plot structure. Antonio's willingness to help his friend, and Shylock's insistence on collecting the pound of flesh drive much of the plot and characterization.
Your main focus should be on the nature of the friendship itself, and what is sometimes called the "client-patron" relationship. In one sense, it appears that the friendship is unequal, with Antonio helping Bassanio and Bassanio the main beneficiary of the association. While that is true financially, in this period, part of prestige for wealthy people was the size and importance of their networks of what were called "clients", poorer friends who associated with them and depended upon them. As Antonio builds a network of friends and help them, he becomes more powerful and well-connected, as one can see when his network collaborates to help him in his trial. Thus for the main part of your project you might want to analyze the friendship in terms of the concept of patronage networks. An interesting contrast is how the social exclusion of the Jews from the Christian society of Venice limits their abilities to create such powerful networks and puts a Jew such as Shylock at a disadvantage in any conflict with Christians.