How do you wire multiple lights and a split receptacle to 3-way switches?
If the switches you are using are typical switches and not the new techno type gizmos which require neutrals, then all you need to do is replace that switch with a three way switch and add a second three way where you want the second switch to be.  Pull a piece of Romex (3 conductor cable with ground) between the two switches. 

Use the red and white in that cable as travelers between the (2)- 3 way switches and the black as your switchleg.  That black wire in that cable will terminate underneath the black screw at your new switch location but tie into your wire feeding the lights/receptacle ('red wire in your drawing') at your switchbox that you already have in place.   

The hot feed (in your drawing above) will terminate underneath the black screw of the three way switch installed at that box. 

Remember, put a piece of red or black tape on the white wire in the cable so that others servicing the box down the road will know that white wire is not a neutral wire.