You can create a new material as per your requirement if the same is not available in the existing dataset.
To create a new material for your project, go to Data Manager tab from the ribbons available at the top of the screen and then to Materials toolbox as shown below :
Under the newly opened Materials Manager tab, you would find list of existing constructions and materials available for the project. To create a new material, go to the Materials section and click on New.
A window will appear asking to fill primary details for the new material. Select the category from the drop-down as shown and provide a new name for the material. Type and class should also be provided from the same window. After filling the details asked, click Ok.
Once clicked Ok, the newly created material will be shown in the catalogue of existing materials, and all the necessary parameters need to be filled in the material details window as shown below. After filling in the details, click apply at the bottom.
After clicking Apply, the new material will be created and set for using the same into a construction as per your requirement.