Usually refluxing means the mixture is boiling and the solvent vapours are condensing in a condenser (reflux literally means "flowing back", i.e. he solvent is flowing back from the condenser into your flask).
Therefore the temperature of your mixture should be approximately the boiling point of your solvent (a bit higher because of dissolved reagents).
Condensation should occur in the lower 2/3 of the condenser, if it is higher you need more cooling water (higher flow rate) or a bigger condenser or turn the temperature down a bit. Otherwise you risk losing your solvent and running your reaction dry.
If solvent vapours do not reach the condenser (no solvent dripping from condenser) then you need to turn up the temperature.
If you're using a water or oil bath to heat your reaction, the temperature of the bath has to be 10 to 20 °C higher, to compensate for loss during heat transfer. (water bath is only good to about 60 °C, PEG oil up to about 160 °C, silicone oil up to 200 °C).
If you're setting this up for the first time, you should ask an experienced chemist to check your setup before heating it up.
Thank you for your answer. Please can you tell me that which solvent can I use instead of dioxane if it is not available?
I’m sorry, since I don’t know anything about your reaction, it’s impossible for me to recommend a suitable solvent. Also I don't know what alternative solvents would be available to you.