Hi,
The approach you take depends on how reliable you want your model to be. Here is the basic explanation of the steps.
First, you choose a set of variables in each dimension (CA, IS, ES, FS) that you want to include in your SPACE matrix model.
Second, you assign ratings to them (usually 1 to 6, but it can be 1 to 10 too). You can assign those ratings based on your personal estimate, but if you have the opportunity to do a survey, your model will be more robust. You can create a survey with your variables, and ask the recipients to rate them - then you add up all the ratings and convert them to your original scale. You can also create a list of indirect questions for each variable in your model and distribute that in your survey. There are many options.
Third, calculate averages.
Fourth, plot values.
See here for more details on
SPACE matrix example and
QSPM matrix example.
Let me know if you have more questions.
Note: Remember that weights have to add up to 100%.
Note: The
SPACE matrix model uses ratings. The
QSPM matrix model uses weights and ratings. They are both subjective estimates. See the two links posted above.