How you print this?

Can someone help me.
I don't know how to print this?

First, the part will export as STL with the same orientation it has in your drawing. You need to rotate it so that the bottom of the part (in the orientation you have shown) is in the XY plane, not the YZ plane as shown. That will put the large flat area on the bed plate when printing. The overhang along the left side of the part will have to be printed by turning on support material in the slicer. If you're using Cura, turn on support and select "everywhere". If using Slic3r, just turn on support material.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

You can also print a beam that fits on the overhang and place it with a little bit of adhesive just before the first unsupported layer prints. This way you can get a cleaner print.

Import the file into meshmixer, it's free to download; produces good easy to remove support [www.meshmixer.com]
it also looks at the model and points out the overhangs.

You can align the faces in meshmixer but I find easier to use netfabb basic [www.netfabb.com]
In drawing/image you posted the face which is facing you would be IMHO the best face to place upon the print bed, turn on support and it just needs to support the gap between the edge and the angle mount. Align the print to the print bed so all lines are 90 degrees to the bed in a vertical direction. You can also add your own support when you design the model, the normal rule for overhangs is angles no more than 45 degrees in relation to the print bed.

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Supporting 3D Printers with Parts and Build services.
Printer: Ormerod 2 (528.4) Duel extruder set-up with Aluminium X-Rib, RRPro Firmware v1.11-ch (2016-04-08)

I've had a couple of prints with similar features that I've designed with a single-nozzle-thickness wall supporting the edge of the feature. Then the feature can be built as a bridge instead of an overhang, and with a pair of diagonal cutters and a file, the wall comes off pretty easily and fairly cleanly. I've had good success with this approach. YMMV.

Thanks guys.
I already have flaten down this part by -90 degrees so it prints only few milimeter height.
But have problems with that part which is unsuported by material.
I use slicer (repetier) and will try wit supporting material function.

Yes I can ...