How to cite the supplemental material from the main text?
There are many different ways how to cite supplementary data/supporting information - whatever you'd like to call it. In general, your title for the supplementary data is perfectly valid. Within the supplementary data, tables and figures including pseudocode are typically numbered in a similar way as in the main text with the exception that they are labeled with the prefix "S" for supplementary/supporting. 

Say you have figures (Figure S1, S2, ...), table (Table S1, S2...) and some equations in the supplementary data, there are several possibilities to cite them:


If you want to refer to the supplementary data, you might just do so, i.e.: For detailed information, see the supplementary data/supporting information.
If you want to elaborate on an aspect with further data in figures and tables, you refer to them similarly to main figures and tables, i.e.: see Figure S1, or cf. Table S1
In the case of pseudocode, the best way probably is to format them as figures and label them as such including the appropriate references (see above).
In the case of equations you might refer to them as follows: for detailed calculations please refer to the equations in the supplementary information


Another approach how to enumerate data in general in the supporting information is the prefix "S" followed by a running number, i.e. S1, S2 and so on. This way you can give each part regardless of figure, table, pseudocode or block of equations a title with section index. 


If you want to refer to a section in the supplementary data, you might cite them as follows: see supporting information S1, or for detailed calculations refer to supporting information S2.


EDIT:
As suggested by jakebeal, journals also offer guidelines for authors including formatting of text, and labelling of graphics and tables. If there are not explicit guidelines available previous publications in the same journal are a good indication as well.