I've seen some videos of after effects time remapping for slow motions using the graph editor, and on youtube the graph editor timeline goes straight (left to right),
but mine goes from the bottom left to top right !
Can someone please help me correct this ?
(I'm using After Effects CS6)
There are several different viewing options for the Graph Editor, but only two basic modes: Speed and Value. It sounds like you're viewing the Value graph and you want to be viewing the Speed graph. To switch modes use the second drop down menu from the left at the bottom of the graph editor (it's just to the right of the eyeball).
The Speed graph shows the rate of change of the Value graph. If you look at your current Value graph it is sloping up and to the right at a rate of 1 unit per frame (a slope of 1). When you switch to the Speed graph you'll see that you have a flat horizontal graph with a value of 1 (the rate of change, or slope, of the value graph). The above is all not really necessary to understand but it gives some good background to a few important points about the speed graph:
When the speed graph is sloping upward the change in value is accelerating.
When the speed graph is flat the value is changing at a constant rate.
When the speed graph is sloping downward the the change in value is decelerating.