Just go to "objects" and click on obj reader, select file, open. Then adjust the scale, it will not come in at the exact size you made it, usefully it will be huge, but that will make it easier for you to see.
Adjust the shaders for the models in the internal nodes of the import object node which you will find in the object section of your node view. Make sure the primary texture is at 100% if it renders black you will know that it is not at 100%
Just getting an object in and moving it around is going to be easy for you. After that come back with more questions