Well I'm sorry to say that if you can't do something so simple as making a standard ruler then you really do need to get practising not using off the shelf DXF's.

Just making the rule marks would be a simple and easy execise to write G-code by hand let alone using a dedicated CAD/CAM program. IE: For 150cm length x 30cm width ruler using 6mm ballnose For 1cm rules 50mm long with 100mm long rules every 10cm set in 30mm in from the edge.
(This simple example code doesn't include cutting out the profile and presumes x0y0 is bottom left corner of ruler and z0 is material surface.)

G0 G40 G49 G80 G21 (Initialisation)
z20 (safe travel distance)
x30 y30 ( Rapid move to start point)
z0 ( Rapid Move Z to top of material)
G91 G1 f2000 (Enter incremental mode and set Linear Move & feedrate)
z-2.5 ( plunge 2.5mm)
y100 (Cut first mark)
z3.5 (lift Z with 1mm clearence)
y-100 x10 (back to rule start and increment 10mm)

( Repeat these 4 lines for every 1cm rule mark and every 10cm change y50 & y-50 to 100)
z-3.5 (plunge tool 2.5mm @ 500mm/min)
y50 (cut first rule 50mm long)
z3.5 ( lift Z leave 1mm travel clearence 2.5mm + 1mm)
y-50 x10 ( back to line start and increment 10mm)


So go on give it a whirl you'll be surprised what you can do and having an intended goal really makes learning software easier and more rewarding.!