You can simply perform the following read operation to convert your unstructured data into a Spark RDD:
val rd = sc.textFile("location-of-data")
The above statement would create an RDD, which can further be transformed according to the use case.
Note: 'sc' is the Spark Context variable
If you are looking for an online course to learn Spark, I recommend this Spark Certification program by Intellipaat.