Are you using Sanger reads? If yes, I do not know a web server to do what you want. However, you can download and use locally this tool which is very simple:
If you are looking for a software that will do the job for one gene at a time, you can use cap3 . Put the two sequences in one fasta file and load them to the online server at: http://biosrv.cab.unina.it/webcap3/cap3doc.html#fileformat.
I suggest you to use DNA BASER program. I have tried a few tools and found it is easy and saves a lot of time. you can download it at http://www.dnabaser.com/. it comes with a month free usage which is more than required time to get your contigs. Hope it serves your purpose.