Creating Isochrones with pgrouting - Network set up, locations (from point shapefile) imported into PostgreSQL/PostGIS DB and now?

I want to calculate isochrones representing the accessability of certain locations in a city. So I have set up the pgrouting enabled database, imported the OSM-Roads and created a network (thanks Anita). I have also calculated the "drivetime" of the road segments (time for walking, biking) and created new columns in the network table for this.

Now I have my point shapefile with the locations, which are subject to the accessability research (see screenshot).

My questions are (sorry if these a too trival but I work with a database for the first time).

1. How do I connect these location points from my point shapefile, which i imported into the database to the road network (I assume this is necessary in order to create the isochrones).


2. I then want create 5min, 10min and 15min isochrones (for walking and cycling) for each of my 15 points (locations)

I work on this for weeks now and also tried GRASS where I was at least able to connect my point shape points to the network but the outcome of v.net.iso is not what i am looking for.

A similar problem was discussed in this question but no solution was found. Also this popular example of finnish airports does not help me because I cannot see how the airports were "snapped" to the network from the explanation.

Could anybody please help me with this?