How to connect my HP photosmart 6510 to my computer with no manual

Is it being used Wired or WiFi? It may be asking for the WiFi password.

Or Reset it to Factory Settings.

https://www.google.com/search?q=hp+photosmart+6510+e+reset+password

The problem may be in the paper sensor
it might dusty or not returned to its position
to solve , open rear / duplexer door, look ! clean using air blower

dip the nozzles side of the catridge in ammonia solution for two hours clogged ink will be dissolved and the nozzles are free.

Try to do a reset of the printer to Factory settings

Seen this video how to do a partial reset for 6500 series printer. here's the link you can forward it to 1:48 where he was talking about how to do partial reset HP Multifunction Printer Resets HP Officejet 6500

Try doing a head cleaning, maybe there is the problem, let me know.

hi,5510OR 6510 printhead the same???

Welcome to the club mate :) Throw it out and stop buying new cartridges before you pay double the price of the printer in cartridges... This is a known problem, without any fix. Should I congratulate you on buying a nice disposable printer?

open the docoment click on file in the top left hand corner of the page
scroll down to print preview you can change what you are about to print in percentages
if you dont have the menu bar in the top of screen right click in it select the menu bar
hope it helps

u should first download the cd of your printer then connect it wid ur computer your hp photoshop whatever it is okay do this u ll surely print ur pics whatever okay .... try this ......