In the VPC interface, click Route Tables on the sidebar, then click Create Route Table

In the Create route table interface:
public-route-table
After successfully creating the route table, click Edit routes

In the Edit routes interface, choose Add route

Then add a route with Destination is 0.0.0.0/0 and Target is workshop-01-igw then click Save changes

After successfully creating, switch to the Subnet associations tab and click Edit subnet associations

Choose 2 public subnets we have created then click Save associations

Perform the same steps to create private-route-table-01 for private subnet 1

Add a route with Destination is 0.0.0.0/0 and Target is nat-gw-01 then click Save changes

Choose private subnet 1 then click Save associations

0.0.0.0/0 and Target is igw (to communicate with db instance from outside the vpc)