Hi Alfredo,
Please go through the following code as it may assist you in solving the problem:
Component:

<aura:component>
<div>
    <div>
        <lightning:layout>
            <lightning:layoutItem size="12" smallDeviceSize="12" mediumDeviceSize="12" largeDeviceSize="12">
                <lightning:layout>
                    <lightning:layoutItem size="6" largeDeviceSize="6" mediumDeviceSize="6" smallDeviceSize="6">
                        <lightning:select name="select" label="Month" value="" aura:id="Journal">
                            <option >Select a month</option>
                            <aura:iteration items="" var="marFi">
                                <option value="{!marFi.value}">{!marFi.label}</option>
                            </aura:iteration>
                        </lightning:select>
                    </lightning:layoutItem>
                    <lightning:layoutItem size="6" largeDeviceSize="6" mediumDeviceSize="6" smallDeviceSize="6">
                        <lightning:select name="select" label="Week" value="" aura:id="Journal">
                            <option >Select a week</option>
                            <aura:iteration items="" var="marFi">
                                <option value="{!marFi.value}">{!marFi.label}</option>
                            </aura:iteration>
                        </lightning:select>
                    </lightning:layoutItem>
                </lightning:layout>
            </lightning:layoutItem>
        </lightning:layout>
    </div>
</div>
</aura:component>

And for adding the table dynamically in your component you can go through the following link:
http://sfdcmonkey.com/2017/08/09/add-delete-rows-dynamic/

I hope you find the above solution helpful. If it does, please mark as Best Answer to help others too.

Thanks and Regards,
Deepali Kulshrestha