1) Select Axis->X min, now click on the minimum value on the x-axis. Enter the corresponding x value in the dialog box. Numbers can be entered in many formats including scientific notation (e.g. 1.23E5). Repeat this with X max, Y min and Y max.
2) Choose the axis type under Axis->Scale and select linear, logarithmic or reciprocal scaling.
It is possible to change the axes itself as well as the scaling between log and linear at all time, already selected data points will be saved correctly. Axes can be in arbitrary angles to each other. There is no need to rotate a graph in exactly horizontal position.