There are two types of DSL devices:
1.) A standalone DSL modem, which is used with a standalone router.
2.) A combo device (router/modem) often called a gateway.
If you have a standalone DSL modem (Only one RJ45 output) then you can purchase a standalone wireless router to connect to it.
If you purchase a gateway (Combo DSL modem / router) then the DSL modem and wireless router circuitry are enclosed in a common case.
The ActionTec DSL Gateway is a popular choice with good Amazon reviews. http://isp1.us/reviews/actiontec-gt784wn-dsl-modem-router/
If you want to use your existing standalone DSL modem and add a wireless router then:
Wireless routers are fairly inexpensive. http://www.amazon.com/s/?_encoding=UTF8&linkCode=ur2&camp=1789&creative=390957&field-keywords=wireless%20router&url=search-alias%3Daps&sprefix=wireless%20ro%2Caps%2C490&tag=excharge-20
Pretty much any wireless router will work for your application. As far as the brand goes, the brand is not as important as the model. Some manufacturers release a good model but the next is crap. I would look at the Amazon reviews of models that interest you. Even if you don't buy from Amazon the reviews will tell you a lot about which models to avoid. Look for at least 15 or more reviews with a 4 star or better rating. Read a few and see if they sound like the particular model will work for your application.
FYI:
A fast router or modem does not make your Internet faster.
A router connects two separate networks and manage the traffic between them.
In most home network applications the router connects your local group of computers and devices known as the LAN with the Internet, commonly called the WAN or Wide Area Network.
Your WAN speed is determined by your ISP and is measured in Mbps (Millions of bits per second).
For example if you pay for a 3 Mbps DSL Internet connection, you will get 3 Mbps.
No router will change your 3 Mbps Internet speed.
This Internet connection bandwidth is shared by your entire LAN via your router.
For example if you have a 3 Mbps DSL plan and one user is utilizing 2.5 Mbps of the bandwidth to stream a Netflix movie that only leaves 0.5 Mbps for all of the rest of the users on the LAN.
Fast routers are designed to stream large files on your LAN quickly. The high speed routers permit fast transfer of files between devices connected to your LAN, however WAN speed is still limited by your ISP.
Good Luck...