How do you chat to the guild and send them health kits?
How to talk to guild?
There will be a chat box hidden on the left hand side of your screen with numbers. Touch there and it will open the chat box
Health kits requests pop up on the chat panel when people request them. It doesn't cost you anything to send, the game generates a new one so if you have 0 you can still send and if you have 1000 you'll still have 1000 afterwards