At each side of the railway crossing you need to place road spline point circles on the road (one on each side of the tracks) ... Measure it's height in topography tab, and lower the 2 heights, in the topography tab, by typing in a lower numeral, ie: -0.02 m (or greater/lesser)
If the track measures at 0.00 m ... the road would be -0.02 m (or greater: -0.06 m ... etc ...)
or, with a bit of practice, with the spline tool window open (the same tool window you used to lay the road)
click on the word Advanced on the bottom left of the window to open the advanced spline tools
click on the Spline Height tool (the little "mountain with a red arrow on the top") button on the top left of the advanced tools
move your mouse over a spline point on the road (the white or yellow circle in the road spline)
then either:-
with the left mouse key down, move the mouse slowly up or down - this will adjust the height in steps of about 7 cm.
with the left mouse key down, hold the Ctrl key down while moving the mouse slowly up or down- this will adjust the height in steps of about 1 cm.
Don't worry about being a noob here. We all started as noobs.
Ask questions and you will get answers - the odd grumpy answer included. Just don't make the mistake of making demands (e.g. "gimme that, I want it") as that will generate a lot of angst.
Are you using a XING asset and then connecting the roads and tracks to it, or are you simply placing the road spline over the track?
If you are using the XING type of assets then there things like check rails and crossing boards you could add to the crossing (XING) to make it look right.
Otherwise see pware's response and play with the spline points, and you could then use boat'z ATLS system for the gates http://www.boatztrainz.co.uk/