Just Have Treats Ready, Everytime Your Dog Rolls Over, Give It a Treat. Start With Sit, Then Lay Down, If Lay Down Doesn't Work, Softly Push the Dog Towards teh Ground, While repeating The Word "Down" But Never Say one Word, And Expect The Dog To Know Another Word, Stick With One Word, Dont change halfway through Training. So "Sit" "Down" Then This Is The Tricky Part, Try Forcefully Rolling Your Dog, While repeating This Word, (It Took Me Just Over A Week, But He Forgot Because I Didnt Keep Doing It) Alqays Praise, And Reward Your Dog, As Tehy LOVE Attention..
I do not advise anyone to "forcefully roll your dog over". This might make them dislike the "roll- over" command, and it should be FUN for the dog, remember: All training should be fun!!! Some breeds are easier than others to teach "roll-over" to. Typically, the shorter dogs like dachshunds, beagles, pugs, etc seem more apt to take to it quickly. To teach it I put the dog into a 'down' and take a yummy treat and LURE the dog to roll over. The first few tries I do not expect a full roll, but if they give me even a partial roll, I will give them the treat. gradually I keep practicing until I can get a full roll-over by passing the treat right over the dog's head/nose and have them "follow it over". Do not give the "roll over" command until your dog will reliably roll over following the lure.