Thousands of tutorials to learn from
following general steps to make top down assembly from skeleton model
Step 1
create component in assembly mode then select skeleton model
Step 2
choose default options and click ok
Step 3
skeleton model appears in assembly model tree right click and open it
Step 4
capture the outline of assembly in skeleton model
Step 5
save and close your skeleton
Step 6
back to assembly again create another part this time select solid in subtype
Step 7
choose default options here.
Step 8
place the component wherever you like,it's not known at this stage as where component will be placed,it can be tweaked later
Step 9
open this newly placed part from model tree
Step 10
to copy geometry from skeleton part navigate insert>shared data>copy geometry
Step 11
i have not published geometry from assembly so have to turn off this option
Step 12
from reference tab browse to skeleton part ,you can use default options here
Step 13
from reference tab browse to skeleton part select geometry whatever you need to make part
Step 14
make part with copied geometry save and close
Step 15
when you save the part,it appears in assembly,same way do it for other geometry.
Step 16
completed assembly