I am new to GIS world and been slowly teaching myself Civil 3d. I have been working with importing maps and raster dgn etc., but now I have hit a wall with the contour files being in .gdb format. Is there anyway to convert these file types to shape files for AutoCAD?
If you choose to take the QGIS route, it's as easy as opening a new project and going to Layer > Add Layer > Vector Layer... and be sure to select TYPE = Directory and SOURCE TYPE = OpenFileGDB or ESRIFileGDB
from here you can select the GDB folder and it will load into the Layers pane. Right click the layer > Export > Save Feature As... and choose 'ESRI Shapefile'.
Keep in mind, shapefiles have multiple files that need to be linked with them so you should compress all exported files to the path you chose into a .zip. After that, you should be able to do pretty much anything with it, including bringing it into AutoCAD
There is a free plugin from ESRI called "ArcGIS for AutoCAD". I never used it so I can't really talk about it but it seem designed to handle case like yours.
If you prefer going to the GBD to Shapefile path be avare that shapefile have limitation and you need to take them in account to prevent unwanted result.
From Esri on Shapefile :
[...] shapefiles are acceptable for storing simple feature geometry. However, shapefiles have serious problems with attributes. For example, they cannot store null values, they round up numbers, they have poor support for Unicode character strings, they do not allow field names longer than 10 characters, and they cannot store time in a date field. These are just the main issues [...]