Step 1: Required materials
You'll need (from left to right) :
1. Two 'cup' screws
2. Two (or three) 'eye' screws
3. Two 'S' hooks
(and, at bottom)
4. A length of 'expanding' or 'net' curtain wire
Step 2: Measure the wire
Step 3: Screw in 'cup' screws
The measurement you took in step 2 can now be transferred to the wall. Drill & then screw in the cup screws. Note that the open ends are facing outwards.
Step 4: Put it together
If you prefer a loose mounting, stay with the above configuration. However, if you want a taunt, wall-frictioned holder you need to decrease the length of the expandable wire. I would suggest that about 25% should do it; ie, my original length was 250 mm, so I cut it down to 190 mm. Hey presto. Now that's tight!