First from the information you give, the 261/500 suggests to me that you have a print of some kind.
Your picture was the 261st impression of a maximum of 500. That is not bad, the lower the number the better though. Premium prices go to lowest numbers 1/500 being the best impression. 500/500 the lowest value.
You should be able to Google the artist and possibly there may be a label on the back giving details of the printer as to the type of print, lithograph etc.
You can use these details and e-mail a reputable auction house or art gallery who can tell you more.
Because it is a print, it may not be worth a fortune, but if you like the painting you can still enjoy it.