Hello Yemi,
You usually start with table BUT000 (where you can find the BPs), use the field PARTNER_GUID. You take this value and use it to search table DPR_BUPA_LINK (even though this table is for Role-BP links, there are two types of roles: abstract and concrete) associating BUPA_GUID with the value from BUT000 and reading PARTICIPANT_GUID.
Now, having the PARTICIPANT_GUID, go to table DPR_ENTITY_LINK and search for all entities that have:
ENTITY_TYPE in (TTO, TPO)
RESPONSIBLE - true
CONCRETE_ROLE
- you read field ENTITY_GUID, which stores the Task GUID. Using this GUID, you can now load instances of cl_dpr_task.
Also, you can build joins on these tables for better performance.
Hope it helps!
Tudor