I have a tenant that just moved in on April 15,2009,I have been having problems with collecting her rent ever since she moved in. She is in errors of this months rent and rent is due on the first of the month and she is a tenant at will and also moved other people into the property without notifying me this is putting my home at risk because it's a duplex and the mortgage will be overdue as of the first of the month because I could only pay a partial payment because I am on disability and lost my husband last year and don't know what to do

I live in New Hampshire

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

If she is late on the rent by even one day you can start the eviction process. The applicable law can be found here: CHAPTER 540 ACTIONS AGAINST TENANTS

First you have to serve her with a pay or quit notice giving her 7 days. She has to pay whatever is owed, in full, including late fees by the end of the notice period. If she doesn't, then you have to go to your local housing court and file for an eviction order. At that point a hearing will be scheduled. Unless she pays in full, an eviction order should be issued at the hearing. If she still refuses to vacate, then you hire a sheriff to enforce the eviction order.