I had completed a database in vb.net with access database. Now my question is, how to make it accessible online?
Frankly I'd take your vb.net system and call it a proof of concept. Few web hosts give you an Access database so your vb.net efforts were to flesh out what you wanted the system to do.
By completed a database in vb.net, do you mean completed in Asp.Net? If that's not the case, first complete all the tables updates and so forth in Asp.Net. Then search the web for "web hosting with access database" to host your access database and the complete application in the Internet.
BTW this seems a question to ask in Programming/web development.