Low Melt Solder is a similar substrate to that of white metal models but it melts at 78celcius so it gives a good joint filling propeties and gives a strong mechanical joint (like brazing). Similar to using two part epoxy glue but much quicker and has less mess.

'Dry' run putting joints together to check for position and good fit. (adjust if necessary). Have your soldering iron tip clean (just run on a sponge soaked in water ) and put a small amount of low melt solder on tip.  Put joints togther and paint a small amount of Low Melt Flux on the joint then place tip (with solder) on joint and brisky draw down the joint the solder will follow flux and fill/fix joint, add solder to tip and repeat if required.  Don't leave the tip on joint for too long and it can melt the model. Continue assembling joints until finish then simily wash the model and allow to dry. Paint as required.

Soldering is skill many people think is difficult but its not as hard as people think. The harder stuff to solder is where parts are very small and if iron lingers too long will melt the part. Just be quick or cheat and use a little superglue for those fine detail bits.