I have a collection of short stories. I want to publish them. I need help in this. Should I pay for publishing or are there any agencies that publish/encourage budding short story writers?
Are you looking to get your book published by a publisher or to self-publish?
If you are looking for a publisher, then my question is whether or not any of your individual stories have been published? If the answer is "yes, several of them" then congratulations! You can look for an agent or start submitting your manuscript to publishers. To find publishers, check such resources as Writer's Digest's marketing guides or look for contests somewhere like Poets & Writers, which I believe only lists contests that meet certain guidelines (and are therefore less likely to rip you off by asking for exorbitant reading fees).
If your stories haven't been published in journals or magazines, I suggest you try for that first. Not only will it help get your book published if you already have credits, it will help build an audience for folks who want to buy your book. You can check sites like Writer's Digest marketing guides, Duotrope, and Submission Grinder to help find markets that meet your needs.
If you want to self publish, look to places like CreateSpace (Amazon) for how to go about that. There are other threads which talk about pros and cons for some of the various places, like CreateSpace, that are essentially print on demand (POD). The thing to be aware of is, if some company wants you to pay to print a bunch of your books up front and it will cost you tons of money, run far away. It's a rip off and not needed in this digital age. It's one thing to pay a reasonable fee for some services (like editing) but do a comparison and keep your wallet in your pocket until you are sure.
Right, before you publish them, ask yourself this: Are they finished? Are they ready to be published? Or are they first drafts? If the latter is true, edit them. Watch for any clichés, grammar or spelling errors, or anything else that can hurt your stories. If they have been edited several times already, and you're certain they don't need more editing, then you may skip to the next paragraph.
Does it matter to you how soon you publish the collection? If not, and if you haven't yet published any of them, enter some of them into short story competitions for the time being. If you keep your name the same for all of them, then you should be able to get them published as a collection in a few years.
Most published collections have connections between their stories. They might all be from the same genre of short stories, or they might give similar morals in different ways. Look over your stories and see whether or not they fit in a collection.
In the meantime, search up some publishers. Find out what you can about them, and whether they'll accept short story collections. This is probably the best route to take if you want them published as soon as possible.