After the installation you have to configure the module. So go to the Module Manager and select the cf filtering module.
As with every module, set its position in the template and publish it. Also set it to be displayed on the pages you want.

Basic Settings

Some settings that regard all the filters.

Empty Options Display. Some options won't return products if selected. With this parameter you can set, how these options will be handled.
a. Show as disabled. Displays the options but the user cannot select them.
b. Hide.
c. Show as enabled. The user can select them even if they will return no products.

Index options by search engines. This actually ads or not a “nofollow” to the created links. Links with “nofollow” are not indexed by the major search engines.

Use the varriables from Virtuemart pages.The module can use variables from the pages of Virtuemart. For example can use the category id from the category page or the productdetails page or use the manufacturer id from the manufacturer page. This is like auto selecting options from the appropriate filters using variables from the VM pages.

Common settings in all filters (Categories, Manufacturers, Custom filters)

The cf filtering settings are built in a way that offers control over the functionalities and the display of every type of filter. Each filter has its own pane with its own settings.

Published
A filter has to be published to be displayed in the module. An unpublished filter won't be displayed no matter how the other parameters are set.

Display type
How the options of a filter will be displayed

1.Drop-down list (Single)
2.Radio buttons(Single)
3.Link (Single)

The only way to select multiple options from a filter is to use checkboxes. (PRO package)

Categories Filter settings

Order of Categories
With this setting you can define how the categories will be ordered in the module.

The available options are:
1.Category ordering (No tree) → The categories will be ordered using the ordering numbers you are using in VM.
2.Category Names → Orders the categories by their names in ascending direction.
3.Category Tree → Displays the categories as tree.

Display specific Categories
You can display only specific categories using that setting. All you have to do is to write the ids of those categories separated by comma in the Displayed Categories input.