Going into anothers dream?

If your in the same room as the person and your are both LDing, is it possilbe? How? How do you do things, just think or say I can or I will do this?

It depends whether or not you believe in it. It is commonly called shared dreaming, where you and another person are in a dream together. Though, this should not be mistaken for a dream with that person as a DC. This can be decieving. Please note, that if it does exist (I have not experienced one), then it would be intrusive to “enter” someone’s dreams without their conscent. I don’t know much about shared dreams, but I’m sure some fellows in the Beyond Dreaming forum board do. That board is meant for questions like these.