back to lay or vise versa

[mrmenstig]

im completely new to all this so im am looking for a basic guide for idiots on back to lay betting.
As i understand it if i back at 4:1 then lay at 2:1 i make the difference in profit.
At the moment this does not seem to be the case so i will explain what i am doing and anything you can see would help.
Pick 2nd or 3rd favorite in race.
Back at (e.g.) 4:1 for £2.5 (£7.5 win)
Lay at 3:5 £2 (£5 liability)
so i should make 7.5 - 5 =2.5 do i have this figured out correctly?

[mugsgame]

Use the ladder and the profit traded columns. It does it all for you (the calcs I mean). There are lots of video around that can help you. You have the basic principle correct, which is the main thing.
MG

[mrmenstig]

thanks for the reply ill look into it