Could somebody tell me what to do we want to immagrate to the USA my husband is working already there and me and my children want to go also

What kind of work is he doing in US? What type of visa he has?
Are you legally married to him?

If he has valid work visa such as H-1B, or L-1, then you and your children would be eligible to obtain dependent visas. These are non-immigrant visas, so you have to return to your home country when the visas expire.

His working at a feedlot in Oklahoma (farming) and the person he is working for did tel us we must come and life in the USA so that is what we want to do I think on the paper that is at home know is the visa a H2A but is know a non-immagrant visa. But his visa expired on 31 of Desember and we are afraid that there's know time to do application for the green card. The other thing we want to try and extend his visum and then the boss told my husband that me and the children must come and viset in Desember but somebody told me that wasn't posible?

You are eligible for H-4 visa, but term of stay depends on your husband's visa which in this case is December 31.

How many time's can he exstend his visa can't we just exstend his visum and me and the children go on a H-4 visa and every time he extend his visa can't we also extend ours and at the same time go and se a immagration attorney to apply for a green card?