You can find many long and complicated explanations in grammar books about the use of 'will' and 'shall'. Most of this information is both confusing and outdated. In everyday English these days, virtually the only times we use 'shall' is in the following question forms in the first person: 'Shall I .....?' for an offer: 'You look hot. Shall I open the window a bit?' 'Shall we ...?' for a suggestion: 'Shall we go for a walk?' or 'What shall we do?' (NB even these sound a little old-fashioned, and we'd be more likely to use 'should' in these questions) In all other situations, use will (or 'll) . There are more complex rules and usages, but I really wouldn't worry about them, if I were you. Hope this helps. In all other situations, use 'w

I am just adding to the excellent explanation by Su.KI. There is a subtle difference between "shall" and "will". Will is definite - I am going to do something. Shall is vaguer - I may do something or I may not something. However only a few pedantic people might appreciate that. The distinction would be important in official legal or diplomatic language though.