Forum rules prevent buying/selling/trading until a member has 50+ posts.
But you can ask input on the best way to disposition the collection (ideally posting a few representative images of the collection). Be aware that 1800 stamps is a very small collection and that general worldwide stamps might only be worth a small fraction of catalog value. If your grandmother was very wealthy and spent significant money on the collection, then you may have something that dealers are interested in. Otherwise it might be best to sell it on eBay
, start it at enough to cover the postage, and hope for the best.