How ?

If the phone includes wifi (the type that will connect to a home or cafe wifi network) that's what you can use it for. Check the specs.

You may find the best answer to How is to go into a cafe that does wifi (not cellphone type internet) and ask how to hook up -- some places are quite helpful including, oddly enough, my local McDonalds.

If you already have wifi at home, consult the manual for your router on how to include your new phone in the network (wireless security passphrase etc).