给means"give" or "pass sth.on to sb." In general,it means one thing is given from one to another.
eg:Could u please give me some drink?I am thirsty.
送means"send without pay or reward"
eg:1.John's father sent him to school this morning.
2.Yesterday was my best friend's birthday,so I sent her a lovely hello kitty as her present.
Hope it made sence to you. :)