Tell me how 2 invite the guests
I must give invitations
Matter which I can write in invitations

You can buy packets of invitations for whatever event. The wording will be appropriate, you will just have to write in the time, date and place and send them out to the people you want to attend.

I do agree with the answer above concerning purchasing invitations and what to write in them concerning the time, date and place, but would also like to ask you if this is to invite people to an engagement party of some kind or to a wedding?