I agree with Cedge. OK, I'm also a newbie at milling, but if I use the end of an end mill I see exactly the same patterns as you're showing there. My indexable shell mill, however, makes pretty glass-like surfaces.
If you can feel pronounced ridges between each line, then your mill is out of tram in the x-axis (assuming you were cutting in the y-axis, front-to-back & vice versa). John (Bogstandard) posted a C-o-C somewhere explaining the effects of tram, and being out of tram.
Also, it's hard to tell, but are you taking full cutter-width cuts with little or no overlap? If so, you may be leaving ridges between the cuts, especially if your end mill isn't absolutely 100% on its width on all cutting edges, and dead flat. I don't know what common practice is, but I tend to advance the cutter by .100" (2.5mm) less than its width, so a 1/2" end mill will be advanced by 0.400" to make the next cut.
When you get it all right, even though you can see the lines (like ploughing), it'll still be smooth to the touch with no ridges.
