When you read the manual you should read all the lines to understand the given definition.
For example there is definition for the button in the manual like this:
button(x, y, bmapOn, bmapOff, bmapOver, functionOn, functionOff, functionOver);
Now you have to read more, because you don't know what is x, y, bmapOn and so on.
You read the next lines and this word
Parameters catches your eyes. You can shout; Oh i got it!
The third line after the Parameter writes this:
bmapOn Bmap displayed when the button is switched on; gives also the size of the button.
Now you know you should use a BMAP to show your button, and you know your declaration
SG.pcx will not fit for the proper showing of the button.
You look up for BMAP. You read all the lines and so on. This is the way how you have to use/read the manual.
One hint at the end:
And:
button(350,200,bmapSG,bmapSG,bmapSG,func_on,func_off,Over);