OK, I'm assuming . . .
(a) that the 'DCP-055W' in your post should actually be 'DCP-7055W) ; and
(b) the you're trying to connect from new. (i.e. that the printer hasn't previously been used with a wired connection. If it has, there's a 'resetting' task that would need to be carried out first).
The first thing to do is to ensure that you've installed the printer software onto your computer.
With your printer within wireless range of your router and turned on, press the 'Menu' button.
Use the 'Up' or 'Down' buttons to get to '3. Network' on the display.
Press 'OK'.
Use the 'Up' or 'Down' buttons to get to '2. WLAN'.
Press 'OK'
Use the 'Up' or 'Down' buttons to get to '3. WPS/AOSS'.
When 'WLAN Enable ?' is displayed, press the 'Up' button to choose 'On'.
When 'Start WPS/AOSS on your wireless access point/router' appears, press the WPS button on your router. (NB: You might need to press AND HOLD the button for a few seconds. With most routers a light will start flashing to let you know that your request to start a connection has been accepted).
Pres 'OK' on your printer.
Hopefully you'll get a message telling you that the connection has been made.
NB AGAIN! Having typed all of that lot out, the more I think about it the more I'm convincing myself that your error up until now has been in only pressing the WPS button BRIEFLY on your router, rather than pressing and HOLDING it (until a light illuminates or starts flashing). That would explain why your printer hasn't 'seen' the connection message arriving.
Good luck!