First of all make sure your monobloc tap is securely tightened to the sink using the nut and fittings that came with the tap. It is important to do this before connecting the flexible connectors as you may not be able to get a spanner on the nut once fitted.
Make sure your flexible tap connectors are the correct length to connect to the rest of your pipe work. Also check the threaded end of the tap connector has a small rubber ‘o ring’ just below the thread. Screw the flexible pipe into the tap by hand and tighten as much as you can. You shouldn’t need any tools for this job and in most cases you won’t be able to get a spanner on. Over tightening can shred the rubber ‘o ring’ and cause the fitting to leak. The ‘o ring’ will seal the gap and create a water tight connection.
Connect the other end of the flexible pipe to the rest of your pipe work using a spanner and a pair of grips to stop the pipe from twisting. Make sure you connect the cold and hot taps to the correct feed! Turn the water back on and test.