Travel to Riverside & I-35.
Go east on Riverside.
After several lights, turn left (north) onto Pleasant Valley.
You will pass through a traffic light at Lakeshore Blvd, and you will eventually see softball fields on your right. This is the Krieg Complex. This is your destination. There will be a sign indicating this. There is also a fireman's practice tower in the parking lot which you are not likely to miss.
The Krieg Complex is located just south of the river, so if you cross over the river and hit Cesar Chavez/1st Street, then you've gone too far.
One thing to keep in mind is that there are two entrances to the complex. If you're coming up Pleasant Valley from Riverside (ie you are heading north on Pleasant Valley), then the first entrance you come to will be at a traffic light. You should use this entrance if you are going to field 1-5. The second entrance is about 100-200 feet up the road past the light, and is not at an intersection. You should use this entrance if you are going to field 6-11.
The field numbers are on the backstops of the fields, and there are signs within the complex directing you to the individual fields. Still, if you haven't been here before, leave yourself extra time to find the field you are looking for.
If you want to get a map to the fields from Google maps, the address is:
517 South Pleasant Valley Road
Austin, TX